Good stuff Shirleen! B&B are definitely likely the lowest cost for lodging.
It’s my first GP too, but I’ve been to Montreal many times for both leisure and business. A couple times during Jazz Festival and Comedy Festival. Downtown and Old Montreal are the places you want to be. I can only imagine GP in town, atmosphere must be even better. Everything is within walking distance and use the subway. The costs are justified a bit when factoring in car rental/gas/parking/insurance/valet, or taxi fares, when living far away, and the traffic jams will be abundant and parking limited. Of course, the limited time you have there, spending it in the car driving/parking would blow a couple of my emotional fuses :)
That’s my two cents with previous experience in this city.